Antivirals Flashcards

1
Q

What are examples of anti-influenza drugs?

A
  1. Amantidine
  2. Osltamivir and zanamivir
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2
Q

What is the mechanism of action of amantidine?

A
  • Early infection: Binds to and blocks M2 channels needed for initiation of fusion process
  • Late infection: Interferes with synthesis and processing of haemagglutinin
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3
Q

What is the mechanism of action of oseltamivir and zanamivir?

A
  • Structural analogues of sialic acid (N-acetylneuraminic acid)
  • Inhibits neuraminidase competitively
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4
Q

What are examples of antiherpes drugs?

A
  1. Aciclovir
  2. Ganciclovir (CMV selective)
  3. Cidofovir (CMV selective)
  4. Foscarnet
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5
Q

What is the mechanism of action of aciclovir?

A

Purine (guanosine analogue)

  1. Within the infected cell, it is phosphorylated to MP form by viral thymidine kinase (only expressed in infected cells)
  2. It is then converted to TP form by cellular kinases
  3. Aciclovir-TP is 30x more selective for viral DNAP than mammalian DNAP and is incorporated into viral DNA
  4. It is missing 3’ –OH group so acts as a chain terminator for viral DNA synthesis
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6
Q

What is the mechanism of action of ganciclovir?

A

Purine (guanosine) analogue

  1. It is converted to ganciclovir-MP by CMV-coded kinase
  2. It is the converted to ganciclovir-TP by cellular kinases
  3. Ganciclovir-TP has greater selectivity for viral DNAP
  4. It also has 3’ –OH so permits chain elongation, albeit at a much decreased efficiency
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7
Q

What is the mechanism of action of cidofovir?

A

Pyrimidine (cytosine) analogue

  • Inhibits CMV DNAP
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8
Q

What is the mechanism of action of foscarnet?

A
  • Analogue of pyrophosphate
  • Selectively inhibits the pyrophosphate binding site on viral DNAP
  • Inhibits cleavage of PPi groups on nucleoside-TPs as they are added to growing polynucleotide chain in DNA synthesis
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9
Q

What are the classes of drugs that can be used to treat HIV infections?

A
  1. Nucleoside reverse transcriptase inhibitors
  2. Non-nucleoside reverse transcriptase inhibitors
    - HIV protease inhibitors
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10
Q

What is the mechanism of action of AZT (nucleoside reverse transcriptase inhibitor)?

A

Thymidine analogues

  • Activated by host cell kinases
  • Selective for RT and is incorporated in place of thymidine
  • Azide group (-N3) in place of 3’ –OH prevents chain elongation, allowing it to act as chain terminator
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11
Q

What is the mechanism of action of non-nucleoside reverse transcriptase inhibitors?

A
  • Binds to allosteric site away form RT active site
  • Probably inhibits conformational changes needed for RT action
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12
Q

What are examples of non-nucleoside reverse transcriptase inhibitors?

A
  1. Nevirapine
  2. Efavirenz
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13
Q

What is the mechanism of action of HIV protease inhibitors?

A

Intermediate analogue of HIV protease

  • Binds to and reacts with HIV protease (Asp protease) active site but reaction cannot be completed (acid resistant –OH prevents acidic attack)
  • Permanently occupies HIV protease active site and acts as suicide inhibitor
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14
Q

What are examples of HIV protease inhibitors?

A
  1. Saquinavir
  2. Ritonavir
  3. Lopinavir
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15
Q

What are available interferon drugs and what are they used for?

A
  1. INF-α-2a: Treat HBV and AIDS-related Kaposi sarcoma

INF-α-2b: Treat HCV

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16
Q

What are other examples of immunomodulating drugs used to treat viral infections?

A
  1. Hyperimmune globulins: Used to treat HBV, VZV and rabies infections
  2. Palivisumab: Monoclonal antibody specific for surface glycoprotein on respiratory syncytial virus